This invention relates to a method of controlling a continuous reheating furnace for heating slabs or the like.
When the heating of continuous slab reheating furnaces is controlled, it is generally required to heat uniformly slabs to a temperature suitable for rolling them and simultaneously heat the slabs to the required final temperature in accordance with a speed required for their rolling line following the continous reheating furnace.
In the control of the type referred to, it has been heretofore the procedure to control the temperature of the atmosphere disposed within continous reheating furnaces to a single value set uniformly in a plurality of control zones into which the furnace is divided. This is because it is extremely difficult to control temperature of a multitude of slabs different in loading, for example, which differ in size from one another respectively resulting in the employment of a single temperature in spite of the differences in the loading or size of the slabs.
In order to maintain the control of the delivery temperatures of slabs by an electronic computer there have been known control methods of the type calculating the heat transfer between a continuous reheating furnace involved with a heating atmosphere and slabs heated therein from a measured temperature profile within the furnace and controlling the flow rate of a fuel introduced into the furance so as to set the temperature of the atmosphere so as to correspond to an objective value determined by the result of the heat transfer calculation.
Those known control methods have been disadvantageous in that the measured temperature profile is very poor in accuracy because of the small number of thermometers for measuring the temperatures within the furnace, which theremomethers do not necessarily indicate the correct temperatures within the furnace. This is because the thermometers are apt to be affected by associated burners, and that the delivery temperature of the slabs is poor in accuracy because the actual temperature within the furnace reaches the objective value with a time delay.
Accordingly it is an object of the present invention to provide a novel and improved method of controlling the heating of a continuous reheating furnace with a high accuracy.